title: A critical assessment of theoretical methods for finding reaction pathways and transition states of surface processes.
abstract: The performance of a variety of techniques for locating transition states on potential energy surfaces is evaluated within the density functional theory framework. Diffusion of a water molecule across NaCl(001) and HCl bond breaking on the same surface are treated as general test cases; the former is an example of a low barrier diffusion process and the latter an example of a relatively high barrier covalent bond rupture event. The methods considered include the nudged elastic band (NEB), Dewar, Healy and Stewart (DHS), dimer, constrained optimization (CO), activation-relaxation technique (ART) and one-side growing string (OGS) as well as novel combinations of the DHS with growing string (DHS + GS) and DHS plus climbing image (CI-DHS). A key conclusion to come from this study is that the NEB method is relatively fast, especially when just a single (climbing) image is used. Indeed, using more images represents an unnecessary computational burden for our set of processes. The dimer method exhibits variable performance; being poor for the water diffusion processes, which have small activation energies, but much more efficient for the HCl bond breaking process which has a higher barrier. When only a poor initial guess of the transition state geometry is available, the CI-DHS scheme is one of the most efficient techniques considered. And as a means to quickly establish an approximate minimum energy pathway the DHS + GS scheme offers some potential.
authors.affiliation: London Centre for Nanotechnology and Department of Chemistry, University College London, London WC1E 6BT, UK.
authors.forename: Jiří
authors.initials: J
authors.lastname: Klimeš
authors.forename: David R
authors.initials: DR
authors.lastname: Bowler
authors.forename: Angelos
authors.initials: A
authors.lastname: Michaelides
mesh_terms: D000465:Algorithms; D019295:Computational Biology; D004058:Diffusion; D019281:Dimerization; D008956:Models, Chemical; D008962:Models, Theoretical; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water